What class do you dine? People eating in Beijing's many restaurants will now know right away due to an online food hygiene rating system.

As part of the city's campaign for cleaner restaurants, the Beijing Health Bureau has developed the online database so diners can check the hygiene standards of local restaurants that are graded from A (excellent) to D (not qualified).

The rating system has been in effect for four years across China, but because of the Olympics more attention has been paid to the hygiene standards of Beijing eateries.

A woman dines at Xuejun, a C-rated eatery featuring homemade Chinese dishes in the Chaoyang District. [Yang Jie/Chinadaily.com.cn]

The online database reveals that among 47 rated KFC outlets in Chaoyang District, where most Olympic venues are located, two outlets are rated A, one rated C and the rest are Bs.

As an international brand, KFC is known for the standard of service it provides to its customers. So why do some outlets have different hygiene ratings from the Municipal Health Bureau?

It turns out this disparity among the stores is not exclusive to the chicken-maker, but also at burger giant McDonald's whose outlets in the city have A, B and C ratings, though all the 23 rated McDonald's outlets in Chaoyang District have a B rating.

The range of ratings also affect Zhen Kungfu, a Chinese fast-food chain aiming to compete with McDonald's with its "green and nutritional" simmered and stewed food, as well as UBC Coffee, a Taiwanese cafe chain, which operates more than 80 outlets in Beijing.

"We all know that KFC does well in providing standard services, but KFC outlets have different locations, different sizes and the layout of their kitchens naturally vary," said Wang Benjin, deputy director of the Beijing Hygiene Supervision Institute (BHSI) explaining why KFC stores are rated differently.

Ms Li Hong, an associated senior doctor with BHSI says because of high employee turnover and employees having different habits, these can be factors explaining why KFC has a variety of ratings.

"It may just happen that a store mixes raw food with cooked food when the inspectors come to the restaurant. All these factors will affect the ratings the outlets get," explained Li. The rating a restaurant gets is actually "floating" and it can change based upon the results of nonscheduled inspections.